Coupled electrical connector with heat-activated memory locking means

ABSTRACT

An electrical connector comprised of a plug and receptacle coupled together using a screw or bayonet-type coupling and additionally including a heat-activatable, generally ring-shaped locking memory member made of a specially chosen memory alloy, such as 55-Nitinol. The locking memory member is provided with original and intermediate shapes chosen for coaction with predetermined opposed annular surfaces provided on the plug and receptacle so that the application of moderate amounts of heat causes the locking memory member to rigidly lock the plug and receptacle in coupled engagement. The locking memory member additionally includes memory indicating tabs for providing an externally visible indication of the locking provided by the locking memory member.

United States Patent Dorrell i 1 COUPLED ELECTRICAL CONNECTOR WITH HEAT-ACTIVATED MEMORY LOCKING MEANS [75] Inventor: Robert F. Dorrell, Des Plaines, 111.

[73] Assignee: Bunker Ramo Corporation, Oak

Brook, Ill.

22 Filed: Nov. 28, 1972 21 Appl. No.: 310,058

[52] US. Cl 339/90 R, 285/82, 285/187, 339/30, 339/113 R [51] Int. Cl. H01! 13/54, HOlr 13/20 [58] Field of Search 339/30, 89, 90, 278 C,

[56] References Cited UNITED STATES PATENTS 2,540,575 2/1951 Finizie 339/30 X 2,773,710 12/1956 Smith 285/187 2,984,811 5/1961 Hennessey et a1. 339/90 R X 2,988,723 6/1961 Archer 339/30 3,112,146 11/1963 Barnhart 339/30 3,390,900 7/1968 McCormick etalu. 285/89 X 3,411,812 11/1968 Prince et a1 285/187 [111 3,801,954 Apr. 2, 1974 FOREIGN PATENTS OR APPLICATIONS 943,130 8/1961 Great Britain 285/187 Primary ExaminerBobby R. Gay

Assistant Examiner-Lawrence J. Staab Attorney, Agent, or FirmFrederick M. Arbuckle; N. Cass [57] ABSTRACT An electrical connector comprised of a plug and receptacle coupled together using a screw or bayonet- 14 Claims, 10 Drawing Figures 1 i COUPLED ELECTRICAL CONNECTOR WITH HEAT-ACTIVATED MEMORY LOCKING MEANS BACKGROUND OF THE INVENTION The present invention relates generally to electrical connector devices, and more particularly to means and methods for improving the rigidity and reliability of mechanically coupled electrical connectors.

It is an existing problem in the art of electrical connectors that difficulties arise in providing rigidity and reliability when mechanically coupled electrical connections are subject to stresses, such as shocks and vibrations, and/or are required to operate in severe environments presenting widely varying or extreme conditions. It will be appreicated that this problem is made more difficult where rapid coupling of connectors is a featured requirement.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide improved means and methods for significantly improving the rigidity and reliability of mechanically coupled electrical connectors.

Another object of the invention is to provide improved rigidity and reliability while still permitting rapid coupling of the electrical connectors.

A further object of the invention resides in the employment of a design for obtaining increased rigidity and reliability which also permits readily obtaining electrical safety connections between the coupling and connector members without requiring the special safety wiring normally provided for this purpose.

Still another object of the invention is to provide means and methods for materially increasing the rigidity of mechanically coupled connectors after coupling thereof in a conventional manner.

A still further object of the invention in accordance with the foregoing object is to provide externally visible means for indicating that the said materially increased rigidity has been provided for the coupled connectors.

Yet another object of the invention is to provide connector constructions in accordance with the foregoing objects which are relatively simple and economical.

The above objects are accomplished in preferred embodiments of the invention by connector constructions which, in a'novel manner, incorporate and take advantage of a material having controllable mechanical memory properties. More specifically, this metallic alloy has the property that, after an object made of the alloy is set to an original shape at a predetermined elevated temperature, the alloy can then be deformed at a lower temperature into a desired intermediate shape. By application of moderate amounts of heat, the alloy can subsequently be returned to the original shape while exerting considerable force.

In particular preferred embodiments of the invention described herein, electrical connectors comprising a plug and receptacle are constructed and arranged to be mechanically coupled together using conventional screw or bayonet coupling means. In accordance with the present invention, each of these preferred electrical connectors also include a locking memory member made of a memoy alloy having the properties described above, and having specially chosen original and intermediate shapes. The conventional coupling of the plug and receptacle isaccoinplished while this locking memory member has its intermediate shape. Then, in order to increase the rigidity and reliability of the coupling, heat is applied to cause the locking memory member to return to its original shape, which original shape is chosen in conjunction with cooperating means provided on the plug and receptacle so as to'materially increase the forces holding the plug and receptacle together.

In accordance with another feature of the invention, the locking memory member preferably also includes an indicating tab having intermediate and original shapes chosen so that an externally visible indication is provided for indicating that the memory member has been returned to its original shape.

In accordance with a further feature of the invention, the memory alloy employed for the locking memory member is chosen so that by the application of appropriate cooling, sufficient relaxation of the locking memory member toward its intermediate shape may be obtained to permit the plug and receptacle to be uncoupled when desired.

The specific nature of the invention as well as other objects, features, advantages and uses thereof will become apparent from the following description of preferred embodiments of the invention taken in conjunction withthe accompanying drawings in which:

BRIEF DESCRIPTION'OF THE DRAWINGS FIG. 1 is a longitudinal view with portions broken away of a first embodiment of the invention illustrating a screw-coupled electrical connector employing a locking memory member-in accordance with the invention,

the locking member being shown in the unactivated showing the locking memory member in the activated condition. FIG. 6 is a longitudinal view with portions broken away of a second embodiment of the invention illustrating a bayonet-coupled electrical connector employing another form of locking memory member in accordance with the invention, the locking memory member being shown in the unactivated condition.

FIG. 7 is a front view of the locking member employed in the embodiment illustrated in FIG. 6.

FIG. 8 is a cross-sectional view of the locking member of FIG. 7 taken along the lines 8-8 thereof.

FIG. 9 is a fragmentary cross-sectional view similar to FIG. 6 showing the locking memory member in the activated condition.

FIG. 10 is a cross-sectional view similar to FIG. 8 showing the locking memory member in the activated condition.

DESCRIPTION OF PREFERRED EMBODIMENTS Like designations represent like elements throughout the figures of the drawings.

Referring initially to FIG. 1, reference numeral 10 generally designates a cylindrical electrical connector comprising a plug 12 and receptacle l4 mechanically coupled together using a conventional screw-type outer cou'pling ring 16 rotatably captivated on the plug shell 18 and threadable on the receptacle shell 20. As will become more evident later on herein, the primary feature of the present invention resides in the inclusion in the connector of a locking memory member which, when activated as illustrated in FIGS. 3 and 5, serves to materially increase the rigidity and reliability of the coupling provided between the plug 12 and receptacle 14.

In a conventional manner, the plug 12 and receptacle 14 include insulating bodies 22 and 24 respectively disposed within the plug and receptacle shells 18 and 20 and having respective mating contacts 26 and 28 provided therein, all as typically illustrated in FIG. 1. It will be understood that although FIG. 1 shows only the one pair of mating contacts 26 and 28, many more can be provided in a similar manner.

Also in a conventional manner, an O-ring 30 is provided in an appropriate groove 31 in the inner surface of the receptacle shell 20. The O-ring 30 engages the outer surface of the plug shell 1850 as to provide sealing for the coupled connector.

Now considering the manner in which coupling is provided between the plug 12 and receptacle 14 in more detail, it will be understood from FIG. 1 that the right end of the outer coupling ring 16 (as viewed in FIG. 1) is provided with interior threads 32 which permit the coupling ring 16 to be screwed onto mating threads 36 provided on the periphery of the receptacle shell 20. To the left of these interior threads 32,the coupling ring 16 is provided with an interior groove 34 which receives a resilient captivating washer 36 and together with a flange 38 provided on the plug shell 18 rotatably captivates the coupling ring 16 thereon.

As also shown in FIG. 1, the left end of the coupling ring 16 additionally has a perpendicularly depending portion 40 providing an annular surface 42 spaced from an opposing annular surface 44 provided by the left shoulder of the plug shell flange 38, thereby forming an annular cavity 46 between the coupling ring 16 and the plug shell 18. It is in this annular cavity 46 between the opposing annular surfaces 42 and 44 that the locking memory member 25 is disposed in accordance with the invention.

Referring now to FIGS. 2 and 3 along with FIG. 1, it will be understood that the memory locking member 25 may typically be provided in the form of a ring or washer with serrated outer surfaces 25a and also advantageously including circumferentially spaced memory tabs 25b extending therefrom. As pointed out previously herein, the memory locking member 25 is made of a material having controllable mechanical memory properties. In the preferred embodiments being considered herein, the memory material is preferably a metallic alloy comprising an equiatomic nickel-titanium intermetallic compound containing approximately 53 to 57 percent by weight of nickel with the balance titanium. This alloy is customarily referred to in the art as 55-Nitinol.

The mechanical memory properties of alloys such as 55-Nitinol are only partially understood in the art, and are believed to be a result of a reversible stressinduced, martensitic transformation. An original memory shape may be set into the alloy at an elevated temperature which is typically about 900F for 55-Nitinol.

This original shape will be retained after the alloy is cooled. The alloy may then be deformed to a desired intermediate shape. Return to the original shape may then be subsequently accomplished when desired by the application of moderate amounts of heat to bring the alloy to a predetermined transitional temperature range which may be varied by appropriate choice of the particular alloy composition. For 55-Nitinol, a transitional temperature range of 60F to 300F may be provided by appropriately changing the percentage of nickel and/or substituting cobalt for nickel on an atomfor-atom basis. The shape recovery temperature range is also dependent on the specific processing history of the alloy. During return of the alloy to its original shape, very considerable force can be exerted thereby so that much mechanical work can be accomplished. Further details concerning SS-Nitinol can be obtained from the article What You Can Do With That Memory Alloy, Materials Engineering, 70, pp. 28-31 (October 1969).

In the light of the above discussion of the properties of the type of memory alloy from which the locking memory member 25 is made, the particular original and intermediate shapes chosen for the locking memory member 25 will now be considered in more detail, the intermediate shape being illustrated in FIGS. 13 and the original shape being illustrated in FIGS. 4 and 5. As illustrated in FIGS. 4 and 5, the locking memory member 25 is typically set in accordance with the invention to an original shape having a slightly bowed cross-section with the four circumferentially spaced memory tabs 250 being bent so as to extend radially therefrom as shown. Prior to assembly in the electrical 25 when in its intermediate shape are chosen in the preferred embodiment being considered so that the locking memory member 25 can readily be accommodated within the annular cavity 46 provided therefor (as illustrated in FIG. 1) without interfering with the normal coupling of the receptacle l2 and plug 14 using the screw type coupling ring 16. As also illustrated in FIG. 1, the coupling ring 16 is designated so as to provide sufficient clearance 48 to permit the memory tabs 25b to extend beyond the ring 16 to an externally visible position.

When it is desired to lock the receptacle 14 and plug 12 in coupled engagement, sufficient heat is applied to bring the locking memory member 25 to its transitional temperature range for recovery of its original shape. As will be understood from FIGS. 4 and 5, the original shape of the locking memory member 25 is such that a considerable force is exerted on the opposed annular surfaces 42 and 44 to thereby provide a highly rigid coupling of the plug 12 and receptacle 14. In addition, by provision of the serrated outer surfaces 25a, a serrated engagement is obtained between the locking memory member 25 and the opposed annular surfaces 42 and 44 so as to provide metal-to-metal bottoming which eliminates the need for safety wiring of the coupling ring 16.

As will also be evident from FIGS. 4 and 5, the return of the memory tabs 25b to their original shape will provide an externally visible indication that the locking memory member 25 has been activated.

A second embodiment of the present invention directed to a bayonet-coupled type of electrical connector will next be considered with reference to FIGS.

Referring initially to FIG. 6, reference numeral 50 generally designates a cylindrical electrical connector comprising a receptacle 62 and plug 64 mechanically coupled together using a conventional bayonet-type of coupling ring 66 rotatably captivated on the plug shell 70 and engageable with a cooperating lug 69 provided on the receptacle shell 68. In a conventional manner, the receptacle 62 and plug 64 include insulating bodies 72 and 74 respectively disposed within the plug and receptacle shells 68 and 70, and having respective mating contacts 76 and 78 provided therein, all as typically illustrated in FIG. 6. Although only a single pair of mating contacts 76 and 78 are shown in FIG. 6, it will be understood that many more can be provided in a similar manner.

Also, in a conventional manner, an O-ring 80 is provided in an appropriate groove 81 of the receptacle shell 68 for engagement with the outer surface of the plug shell 70 in order to provide sealing for the coupled connector.

Now considering the coupling between the receptacle 62 and plug 64 of FIG. 6 in moredetail, it will be understood that a helical interior groove. 82 is provided at the left end of the bayonet-type coupling ring 66 (as viewed in FIG. 6) for cooperative engagement with the lug 69 on the receptacle shell in a manner typical of bayonet-type coupling arrangements.

As will also be understood from FIG. 6, the bayonettype coupling ring 66 additionally provides an interior slot 84 for receiving a flange 86 projecting from the plug shell 70, and for also receiving a locking memory member 90 having the general form of a wave washer and preferably made of 55-Nitinol so as to have the memory properties described previously. It will be understood that this wave washer type of locking memory member 90 is retained inthe annular cavity 92 formed between the annular shoulder 94 of the receptacle flange 86 and an opposed annular surface 96 provided for the coupling ring 66 by an insert 98 threaded into the right end thereof. The locking memory member 90 serves to provide a basically similar memory locking function as described in the embodiment of FIG. 1. In addition, the locking memory member 90, in conjunction with the flange 86, serves to rotatably captivate the bayonet-type coupling ring 66 on the plug shell 70.

Referring now to FIGS. 7-10 along with FIG. 6, the particular original and intermediate shapes chosen for the locking memory member 90 in the embodiment of FIG. 6 will be further considered, the intermediate shape being illustrated in FIGS. 6-8 and the original shape being illustrated in FIGS. 9 and 10. As will best be understood from FIGS. 8 and 10, the wave washer type of locking memory member 90 is typically set in accordance with the invention to an original shape (FIGS. 9 and having a width which is significantly reduced when the locking memory 90 is deformed to its intermediate shape (FIGS. 8 and 9) for assembly in the connector. Also, as in the first described embodiment, the locking memory member 90 is advantageously provided with circumferentially spaced memory tabs 90 bent to extend radially when in their original shape (FIGS. 9 and 110), while being unbent to extend perpendicularly when in their immediate shape (FIGS. 6-8).

It will be evident from FIGS. 6-10, that the width of the locking memory member 90 when in its intermediate shape is chosen so that it can be received within the annular cavity 92 without interferring with the normal coupling of the receptacle 62 and plug 64 using the bayonet-type coupling ring 66, and while also being able to perform its function in captivating the coupling ring 66. As will be seen in FIG. 6, the insert 98 threaded to the coupling ring 66 is designed so as to permit the memory tabs 90a to extend to an externally visible position.

When it is desired to lock the receptacle 62 andplug 64 in coupled engagement, sufficient heat is applied to bring the locking memory member 90 to its transitional temperature range for recovery of its original shape. As will be understood from FIGS. 9 and 10, the original shape of the locking memory member is such that a considerable force is exerted on the opposed annular additionally be provided for the described embodiments. This is advantageously achieved by choosing the composition and processing history of the alloy used for the memory locking members so that, after the receptacle and plug of the connector are locked by return of the locking memory member to its original shape, the application of approprite cooling will cause at least a partial return of the locking memory members to their intermediate shape so as to permit uncoupling of the receptacle and plug.

Obviously, many modifications and variations of the invention are possible in view of the above teachings. Therefore, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts specifically described or illustrated, and that within the scope of the appended claims it may be practiced otherwise than as specifically described or illustrated.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An electrical connector comprising:

a plug and receptacle,

said plug and receptacle each including a shell containing at least one insulated electrical contact, coupling means for coupling said plug and receptacle together with their contacts in mating engagement,

said coupling means and one of said plug and receptacle providing surfaces which form a receiving said change of shape of said locking means being chosen to cause said locking means to bear against said surfaces of said receiving cavity in a manner which rigidly locks said plug and receptacle together in coupled engagement.

2. The invention in accordance with claim 1, wherein said material is a metallic alloy material chosen so that the application of cooling thereto after return to its original shape will produce sufficient relaxation to permit uncoupling of said plug and receptacle.

3. An electrical connector comprising:

a plug and receptacle,

said plug and receptacle each including a shell containing at least one insulated electrical contact, said plug and receptacle also including coupling means for coupling said plug and receptacle together with their contacts in mating engagement. said coupling means and one of said plug and receptacle providing surfaces which form a receiving cavity, and

heat activatable locking means disposed in said receiving cavity and made of a metallic alloy material having the property that after being physically deformed into an intermediate shape is returnable to an original shape by the application of heat, said intermediate and original shapes being chosen so that the return of said locking means to said original shape rigidly locks said plug and receptacle together in coupled engagement.

4. The invention in accordance with claim 2, wherein said metallic alloy material is 55-Nitinol.

5. The invention in accordance with claim 3, wherein said metallic alloy material is further chosen so that the application of cooling thereto after return to its original shape will produce sufficient relaxation to permit uncoupling of said plug and receptacle.

6. The invention in accordance with claim 3, wherein said coupling means includes an outer coupling ring captured on one of said plug and receptacle shells and capable of being coupled to the other shell.

7. The invention in accordance with claim 6, wherein said coupling means is of the screw-thread type.

8. The invention in accordance with claim 6, wherein said coupling means is of the bayonet type.

9. The invention in accordance with claim 1, wherein said receiving cavity is of annular shape and wherein said locking means is of ring shape.

10. The invention in accordance with claim 2, wherein the abutting surfaces of said cavity and locking means are serrated to provide for serrated engagement therebetween.

11. The invention in accordance with claim 1, wherein said locking means includes indicating means which exhibits an externally visible change when said locking means is returned to its original shape.

12. The invention in accordance with claim 6, wherein said locking means also serves to captivate said coupling ring on one of said shells.

13. A method of locking a plug and receptacle in rigid coupled engagement, said method comprising:

providing a plug and receptacle and coupling means therefor so that surface on said coupling means form a receiving cavity with surfaces of one of said plug and receptacle,

coupling said plug and receptacle with said coupling means with a locking member disposed in said receiving cavity, said locking member being made of a metallic alloy material having the property that after being physically deformed into an intermediate shape is returnable to an original shape by the application of heat; and

heating said locking member sufficiently to cause it to return to its original shape, said intermediate and original shapes being chosen so that the return of said locking member to said original shape causes said plug and receptacle to be locked together in rigid coupled engagement.

14. A method of locking a plug and receptacle in rigid coupled engagement followed by uncoupling thereof, said method comprising:

providing a plug and receptacle and coupling means therefor so that surfaces on said coupling means form a receiving cavity with surfaces of one of said plug and receptacle,

coupling said plug and receptacle with said coupling means with a locking member disposed in said receiving cavity, said locking member being made of a metallic alloy material having properties such that after being physically deformed into an intermediate shape is returnable to an original shape by the application of heat and which thereafter can be relaxed by the application of cooling,

heating said locking member sufficiently to cause it to return to its original shape, said intermediate and original shapes being chosen so that the return of said locking member to said original shape causes said plug and receptacle to be rigidly locked together in coupled engagement, and

uncoupling said plug and receptacle by cooling said locking member to cause sufficient relaxation thereof to permit said uncoupling.

* v a e 

1. An electrical connector comprising: a plug and receptacle, said plug and receptacle each including a shell containing at least one insulated electrical contact, coupling means for coupling said plug and receptacle together with their contacts in mating engagement, said coupling means and one of said plug and receptacle providing surfaces which form a receiving cavity, and heat-activatable locking means disposed in said receiving cavity and made of a material which changes shape in response to application of a predetermined amount of heat thereto, said change of shape of said locking means being chosen to cause said locking means to bear against said surfaces of said receiving cavity in a manner which rigidly locks said plug and receptacle together in coupled engagement.
 2. The invention in accordance with claim 1, wherein said material is a metallic alloy material chosen so that the application of cooling thereto after return to its original shape will produce sufficient relaxation to permit uncoupling of said plug and receptacle.
 3. An electrical connector comprising: a plug and receptacle, said plug and receptacle each including a shell containing at least one insulated electrical contact, said plug and receptacle also including coupling means for coupling said plug and receptacle together with their contacts in mating engagement. said coupling means and one of said plug and receptacle providing surfaces which form a receiving cavity, and heat activatable locking means disposed in said receiving cavity and made of a metallic alloy material having the property that after being physically deformed into an intermediate shape is returnable to an original shape by the application of heat, said intermediate and original shapes being chosen so that the return of said locking means to said original shape rigidly locks said plug and receptacle together in coupled engagement.
 4. The invention in accordance with claim 2, wherein said metallic alloy material is 55-Nitinol.
 5. The invention in accordance with claim 3, wherein said metallic alloy material is further chosen so that the application of cooling thereto after return to its original shape will produce sufficient relaxation to permit uncoupling of said plug and receptacle.
 6. The invention in accordance with claim 3, wherein said coupling means includes an outer coupling ring captured on one of said plug and receptacle shells and capable of being coupled to the other shell.
 7. The invention in accordance with claim 6, wherein said coupling means is of the screw-thread type.
 8. The invention in accordance with claim 6, wherein said coupling means is of the bayonet type.
 9. The invention in accordance with claim 1, wherein said receiving cavity is of annular shape and wherein said locking means is of ring shape.
 10. The invention in accordance with claim 2, wherein the abutting surfaces of said cavity and locking means are serrated to provide for serrated engagement therebetween.
 11. The invention in accordance With claim 1, wherein said locking means includes indicating means which exhibits an externally visible change when said locking means is returned to its original shape.
 12. The invention in accordance with claim 6, wherein said locking means also serves to captivate said coupling ring on one of said shells.
 13. A method of locking a plug and receptacle in rigid coupled engagement, said method comprising: providing a plug and receptacle and coupling means therefor so that surface on said coupling means form a receiving cavity with surfaces of one of said plug and receptacle, coupling said plug and receptacle with said coupling means with a locking member disposed in said receiving cavity, said locking member being made of a metallic alloy material having the property that after being physically deformed into an intermediate shape is returnable to an original shape by the application of heat; and heating said locking member sufficiently to cause it to return to its original shape, said intermediate and original shapes being chosen so that the return of said locking member to said original shape causes said plug and receptacle to be locked together in rigid coupled engagement.
 14. A method of locking a plug and receptacle in rigid coupled engagement followed by uncoupling thereof, said method comprising: providing a plug and receptacle and coupling means therefor so that surfaces on said coupling means form a receiving cavity with surfaces of one of said plug and receptacle, coupling said plug and receptacle with said coupling means with a locking member disposed in said receiving cavity, said locking member being made of a metallic alloy material having properties such that after being physically deformed into an intermediate shape is returnable to an original shape by the application of heat and which thereafter can be relaxed by the application of cooling, heating said locking member sufficiently to cause it to return to its original shape, said intermediate and original shapes being chosen so that the return of said locking member to said original shape causes said plug and receptacle to be rigidly locked together in coupled engagement, and uncoupling said plug and receptacle by cooling said locking member to cause sufficient relaxation thereof to permit said uncoupling. 